Photo of product family: Ducts

Circular Ventilation Ducts

Circular ducts used in ventilation systems are spiral ducting, seam-welded and butt-welded ducts. The most popular type of ducting is a spiral duct. Spiral duct is often referred to as "spiro" duct/tube because one of the most popular brands of tubeformers (spiral duct machines) are manufactured by Spiro International S.A.

Duct sizes

Spiral ducting and fittings are produced in diameters range 80 mm to 1600 mm of galvanised steel, aluminium and stainless steel sheet. The standard length of a spiral tube - 3 metres. For easier delivery, we can manufacture shorter spiral ducting, e.g. 1-1.5 meter long sections to be transported on the pallets or in crated boxes. Check our Good Practices for Spiral Duct Installation, Transport and Storage.

Galvanised ducting is a standard type of ducting, though for more aggressive or special environments e.g. swimming pools or food industry buildings we can offer stainless steel spiral ducting with the addition of molybdenum. If You're looking for chemically resistant ductwork - see our chemically resistant plastic ducting.  

The thickness of the sheet for typical elements depends on the diameter and equals to 0.5 - 1.5 mm. Spirally wound duct sizes above 250 mm diameter are additionally corrugated to increase their negative pressure resistance.

Alnor Ventilation Systems
Krakowska 10 Avenue
05-552 Wola Mrokowska

tel. +48 22 737 40 00